Surface Stress Effects in Nanostructured Si Anode Particles of Lithium-ion Batteries

Abstract

The rising demands for high energy storage systems with greater energy and power densities than the current, commercial ones, have moved our interest toward low-weight electrode materials. Silicon, with a very high theoretical capacity of 4200 mAh/g, is the best replacement for conventionally used graphite (372 mAh/g) as the anode material for lithium-ion batteries (LiBs). The drawback associated with the usage of silicon is that, in a fully lithiated state, silicon expands volumetrically up to more than three times its original volume. The advancement in manufacturing technology has given the researchers the required impetus for exploring and exploiting the various rewards of nano-technology. The use of nanostructured Si anode particles evades few major problems satisfactorily, without compromising with the capacity of the battery. As we venture into the lower dimensions, the ratio of surface to volume increases and hence, the surface effects become more prominent. The present work caters to developing a surface stress formulation for the specific case of an annular/hollow cylindrical silicon anode particle. The formulation is validated with the pre-established results examining the effects of surface stress on diffusion-induced stresses in anodes consisting of spherical nanoparticles. It has been observed that surface stresses have a relaxing effect on bulk stresses. Here, relaxation refers to a shift in the stress trends in the negative (compressive) direction. With a decrease in the initial size (radius of curvature) of the cylindrical particles, the surface stress increases, thus increasing the extent of this relaxation. It is further affected by the rate of influx of lithium atoms. With an increase in the influx rate, surface stress increases. The surface stresses also affect the plastic stretches occurring in a particle, beyond the yield stress limit. Although the present discussion is limited to the context of lithium-ion batteries, the formulation can be generalized to assess the surface stress effects in axisymmetric nanostructured particles in any chemo-mechanical environment, undergoing finite deformation.

The original version of this chapter was revised: The chapter title “Surface Stress-induced Degradation of Electrochemical Performance of Cylindrical Silicon Anode Particles in Li-ion Batteries” has now been replaced with “Surface stress effects in nanostructured Si anode particles of Lithium-ion batteries”. The correction to this chapter can be found at https://doi.org/10.1007/978-981-15-8315-5_56